A Potential Economic and Efficient Technology Study for Sustained Casing Pressure Mitigation

Abstract

The typical sustained casing pressure mitigation methods usually result of high operational cost and large downhole time consumption, due to the complexity of maximizing annulus micro crack exposure and sealant replacement. It commonly involved with section milling at compromised cementing section via multiple runs, to mill out existing casing and cement sheath where micro channel is existing at, followed by cement replacement tool at independent runs to re-establish cement barrier – to set mechanical barrier as cementing base then run in hole the cement string to perform plugging job. A standard 100 feet cement plug via section milling costs days or even weeks depends on downhole condition, operation parameters control and tools stability.

This paper introduced a new SCP mitigation technology combined perforation, hydraulic washing and cementing in one run, with great economic and efficiency potential, to connect annulus micro cracks by high density perforation, and perform high jetting power hydraulic washing to clean out perforation channels, then replace cement via same tool string to seal off annulus communication path. Compared with standard section milling and cementing operation at same downhole condition, this new tech tremendously reduces operation time from weeks to within couple of hours.

The main challenge for this technology is how to optimize the perforation section to expose all micro channels with effective perforation path after hydraulic washing to enable a success cementing replacement. Failure happens after perforation the circulation and washing can not to be established, or debris isn’t able to be moved during washing, which enables the cement replacement to seal off annulus. This leaves out opportunities for tools performance and operation parameters improvement.